The emergence of antibiotic-resistant bacterial infections remains one of the most serious infectious disease risks in occupational and other settings. In addition, exposures to antimicrobial residues are increasingly being recognized as priority occupational and public health issues. In agricultural environments, an important potential source of exposure to resistant bacteria and antimicrobial residues is reclaimed wastewater used for irrigation. However, exposures to these agents among irrigation workers have not been fully evaluated. Therefore, the long-term goal of this study is to improve understanding of wastewater irrigation workers'exposures to antibiotic-resistant bacteria and antimicrobials in two regions that are characterized by different climates. The central hypothesis of this proposal is that spray irrigation workers are exposed to these infectious and other agents through both inhalation and dermal routes of exposure. Our specific aims are as follows: 1) To evaluate air, wastewater, dermal swab and nasal swab samples collected during wastewater irrigation activities at sites in Maryland and Texas for the presence of antibiotic-resistant Staphylococcus aureus and Enterococcus spp.;and 2) To evaluate air and wastewater samples for the presence of residues from commonly used antimicrobials, including oxacillin, tetracyclines, and triclocarban. Air, wastewater, dermal swab and nasal swab samples --as well as negative control samples--will be collected at two sites in each region, 4 times throughout the 2-year duration of the study. Recovered bacterial isolates from all samples will be tested for resistance using the Sensititre semi-automated system, and air and wastewater samples will be tested for antimicrobials using an isotope dilution liquid chromatography tandem mass spectrometry method. The novel data generated in this study will provide new insights into potential infectious disease and other occupational health implications associated with exposures to reclaimed wastewater. This innovative research is a first step towards identifying important emerging exposures among wastewater irrigation workers at a time when the use of reclaimed wastewater is increasing at an impressive rate and will continue to do so in the foreseeable future. The successful completion of this study will address the following NORA sector, cross- sector and emphasis areas: Sector-Agriculture, Forestry &Fishing;Cross-sector-Immune/ Dermal/Infectious Diseases;and Emphasis Area-Exposure Assessment. Public Health Relevance: The goal of this study is to improve understanding of wastewater irrigation workers'exposures to antibiotic- resistant bacteria and antimicrobials in two regions that are characterized by different climatic conditions. The novel data generated in this study will provide new insights into potential infectious disease and other occupational health implications associated with exposures to reclaimed wastewater. This innovative research is a first step towards identifying important emerging exposures among wastewater irrigation workers at a time when the use of reclaimed wastewater is increasing at an impressive rate and will continue to do so in the foreseeable future.